Air precleaners that separate heavier-than-air particles from the air used in combustion type engines are known. All of these known air precleaners are functional, but do not address the needs of current combustion engine designs for extremely low initial restriction and high particle separating efficiency over the broad airflow range with which they are used.
The following is a list of U.S. pat. nos. relating to air cleaning devices:
U.S. Pat. Nos. 2,193,479 2,304,778 2,417,130 2,973,830 3,552,102 3,670,480 3,740,932 3,973,937 4,138,761 4,197,102 4,201,557 4,547,207 5,022,903
An object of the present invention is to provide an improved air precleaner and method for centrifugally ejecting heavier-than-air particulate debris from an air stream which overcome the aforementioned disadvantages of the known air precleaners. More particularly, an object of the present invention is to provide an improved air precleaner and method which meet or exceed the requirements for use of the air precleaner in connection with diesel engines, offering significant improvements in debris removal with minimal impact on intake airflow as compared with conventional air precleaners. A further object of the invention is to provide an improved air precleaner which can also be adapted for use on other systems that require ambient air at all environmental and altitudinal applications.
These and other objects of the invention are attained by the air precleaner of the invention, which according to a disclosed preferred embodiment comprises a base; a circular separator chamber connected to the base and including an inner wall with a debris ejection duct therein, and a particle accelerator assembly rotatably mounted in the separator chamber. The base has an inlet for the passage of debris laden air into the air precleaner, a plurality of air inlet vanes angled upwardly with respect to a longitudinal axis of the air precleaner for directing incoming debris laden air into the circular separator chamber as a vortex airflow, and an outlet for the passage of air from the air precleaner after the air has moved through the circular separator chamber for centrifugally removing heavier-than-air particulate debris therefrom by way of the debris ejection duct.
The circular separator chamber of the air precleaner is formed with a toroidal dome in the disclosed embodiment for smooth airflow transition of the vortex airflow moving through the separator chamber in a cyclonic pattern upwardly from the inlet past the debris ejection duct where it is folded over by the toroidal dome for whirlpooling down to the outlet radially inwardly of and through the upwardly moving vortex airflow in the chamber. The inside surface of the separator chamber is configured to minimize resistance to the airflow vortex while directing the airflow vortex to change directions, enter the air outlet passageway in the base, and enter into the intake duct of the associated device such as an internal combustion engine. The air inlet vanes, base and cylindrical toroidal dome separator chamber are also configured to direct the vortex airflow with a minimum of turbulence and airflow restriction.
The toroidal dome of the separator chamber is formed by a circular toroidal arch at an upper end of the separator chamber in the illustrated embodiment. The inner wall of the separator chamber, as seen in a cross section thereof along a longitudinal axis of the air precleaner, slopes inwardly in the direction of the toroidal dome to decrease the cross sectional area of the flow path for the vortex airflow moving through the separator chamber. In the disclosed embodiment, the shape of the separator chamber provides a linear reduction in cross sectional area of this flow path thereby increasing the velocity of the vortex airflow in the chamber and keeping debris in the air circulating around the inner wall of the chamber for ejection through the debris ejection duct.
According to the preferred embodiment, the debris ejection duct extends upwardly along the inner wall of the separator chamber between the air inlet and the toroidal dome. The open area of the debris ejection duct is larger at a lower end thereof and decreases from the lower end to the upper end.
The particle accelerator assembly of the air precleaner includes a central hub and a plurality of curved appendages that arc back from the central hub in a swept-back attitude relative to the direction of the vortex airflow coming off the upwardly angled air inlet vanes. A curved area of the appendages extends downwardly to a passageway of the air outlet of the base. The curved area is cupped in the direction of the airflow vortex in the air outlet passageway for rotationally powering the particle accelerator assembly at a speed greater than the rotational speed of the incoming vortex airflow. This configuration of the appendages produces an outward velocity vector to any air or debris that is impacted by the appendages, thus encouraging ejection from the debris ejection duct.
The particle accelerator assembly further includes a center shaft connected to the central hub. The assembly is rotatably mounted in the separator chamber by way of the center shaft which is rotatably supported by a bearing assembly in an upper end of the separator chamber. The central hub has an outer configuration which forms a smooth transition from a downward arch of the circular toroidal dome of the separator chamber to the bottom of the central hub which ends as a rounded tipped cone centered over the air outlet in the base of the air precleaner. A labyrinth seal is provided between adjacent ends of the central hub of the particle accelerator assembly and the downward arch of the circular toroidal dome of the separator chamber in the vicinity of the smooth transition from the downward arch to the central hub. The labyrinth seal discourages debris migration from the separator chamber to the bearing assembly. This arrangement of the particle accelerator assembly within the separator chamber allows the air precleaner to direct the airflow vortex with a minimum of turbulence and resistance.
The radial outer ends of the appendages of the particle accelerator assembly extend vertically and are contoured to match an inward slope of the circular toroidal dome separator chamber with an equal distance along the entire leading edge of the vertically extending outer ends of the appendages to the debris ejection duct. The vertically extending outer ends of the appendages are wider at their bottom end and narrow in the direction of their top end. Each of the vertically extending outer ends of the appendages have a plurality of outwardly directed strakes formed thereon for entrapping and directing debris into the debris ejection duct. Each of the air inlet vanes is also provided with directional strakes on its windward side for directing the airflow as it passes over the air inlet vanes. The appendages also each have strakes formed into the top and bottom of a leading edge thereof for entrapment of air borne debris, directing the debris down the length of the appendage and depositing the debris in the airflow vortex circulating around the inner wall of the circular toroidal dome separator chamber. As noted above, the improved air precleaner of the invention is powered by the air that is pulled through the inlet thereof and operates on fractional horsepower, resulting in minimal air restriction for maximum particle ejection efficiency.
The debris ejection duct in the wall of the separator chamber extends upwardly at a 90.degree. angle along the inward sloping surface, stopping at the top of the circular toroidal dome separator chamber. The ejection duct is in effect an air scoop that extends into the outermost area of the airflow vortex such that it will eject debris and a small quantity of vortex air from the separator chamber. The debris ejection duct is positioned near normal to the airflow vortex, thus presenting several opportunities for debris ejection while the airflow vortex passes over the air scoop multiple times. The debris ejection duct is tapered from the largest opening at the lower end thereof, to the smallest open area at the top of the duct. This encourages the ejection of debris and minimizes loss of air from the airflow vortex.
The inner wall of the separator chamber in the disclosed embodiment is configured with three circumferential strakes. One strake is located at the bottom of the debris ejection duct, one is in the middle, and one is at the top. These strakes are effective to trap debris and direct it into the debris ejection duct while minimizing any effect on the airflow vortex.
A method of the invention for moving air through an air precleaner for centrifugally ejecting heavier-than-air particulate debris from the moving air comprises drawing debris laden air into the air precleaner, directing the air drawn into the air precleaner into a vortex flow within the air precleaner, increasing the velocity of the vortex flow within the air precleaner for centrifugally ejecting heavier-than-air particulate debris therefrom, and smoothly folding over the vortex flow at one end of the air precleaner by interacting the vortex flow with a toroidal dome of the air precleaner for whirlpooling the moving air back through the vortex flow inwardly thereof to an air outlet of the air precleaner. As noted above, the step of increasing the velocity of the vortex flow within the air precleaner includes moving the vortex flow through a passage in the air precleaner whose cross sectional areas linearly decreases. The velocity of the vortex flow in the air cleaner is also increased by interaction of the vortex airflow with the appendages of the particle accelerator assembly which move through the air at speeds greater than the incoming air.
These and other objects, features and advantages of the present invention will become more apparent from the following description of a preferred embodiment in accordance with the invention when taken in connection with the accompanying drawings.